• Korean Journal of Remote Sensing
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• v.36 no.5_1
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• pp.707-723
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• 2020

In this study, a decision tree type of quality control (QC) method was developed to improve the temporal-spatial representation and accuracy of the visibility data being operated by the Korea Meteorological Administration (KMA). The quality of the developed QC method was evaluated through the application to the 3 years (2016.03-2019.02) of 290 stations visibility data. For qualitative and quantitative verification of the developed QC method, visibility and naked-eye data provided by the KMA and QC method of the Norwegian Meteorological Institute (NMI) were used. Firstly, if the sum of missing and abnormal data exceeds 10% of the total data, the corresponding point was removed. In the 2nd step, a temporal continuity test was performed under the assumption that the visibility changes continuously in time. In this process, the threshold was dynamically set considering the different temporal variability depending on the visibility. In the 3rd step, the spatial continuity test was performed under the assumption of spatial continuity for visibility. Finally, the 10-minute visibility data was calculated using weighted average method, considering that the accuracy of the visibility meter was inversely proportional to the visibility. As results, about 10% of the data were removed in the first step due to the large temporal-spatial variability of visibility. In addition, because the spatial variability was significant, especially around the fog area, the 3rd step was not applied. Through the quantitative verification results, it suggested that the QC method developed in this study can be used as a QC tool for visibility data.

• Journal of Environmental Science International
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• v.26 no.4
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• pp.535-542
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• 2017

This study was conducted to investigate how $PM_{10}$ concentration and Relative Humidity (RH) affected visibility in Jinju, Korea. A 9-yr dataset of 1 h averages for visibility, $PM_{10}$, and RH data was analyzed to examine the correlation between these variables. On average, visibility decreased by 1.4 km for every $10{\mu}g/m^3$ increase in $PM_{10}$ and by 2.1 km for every 10% increase in RH. In general, a negative correlation was observed between visibility and and $PM_{10}$ concentration. However, under conditions of low $PM_{10}$ concentration(< $15{\mu}g/m^3$) and visibility(< 2 km), there was a positive correlation between these two variables. In this case, RH levels were high (> 75%). A high correlation analysis between two variables need to be under control conditions with RH < 75%, $PM_{10}$ $15{\sim}100{\mu}g/m^3$, and visibility > 2 km.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.1
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• pp.48-52
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• 2010

In this paper, we introduce a new path planning algorithm which combines the merits of a visibility graph algorithm and an adaptive cell decomposition. We quantize a given map with empty cells, blocked cells, and mixed cells, then find the optimal path on the quantized map using a visibility graph algorithm. For reducing the number of the quantized cells we use the quad-tree technique which is used in an adaptive cell decomposition, and for improving the performance of the visibility checking in making a visibility graph we propose a new visibility checking method which uses the property of the quad-tree instead of the well-known rotational sweep-line algorithm. For the more efficient visibility checking, we propose two additional improvements for our suggested method. Both of them are used for reducing the visited cells in the quad-tree. The experiments for a performance comparison of our algorithm with other well-known algorithms show that our proposed method is superior to others.

• Journal of the Regional Association of Architectural Institute of Korea
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• v.20 no.6
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• pp.71-80
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• 2018

The path and visibility of nurses in general hospital wards have been treated as architectural planning factors. However, the analysis approach of existing studies shows limitations that only fixed physical elements are considered without considering the behavior of users using space. Consider factors for analysis of ward and models based on this study model. Select a case hospital to apply the analysis technique and conduct the nurse questionnaire and route survey of the hospital. Establish a framework for analysis model applied with the path of nurse movements. The analysis model applies to the case hospital. The analysis results are aggregated to derive design suggestion for reference to the spatial improvement of the ward. Visible visibility to observe the bedside in the nursing station, visibility to observe the beds in the nurse's path, and visibility to observe patients moving in the nurse's path were derived from visual access frequency and exposure frequency. The survey of nurses' movements at the site allowed the nurses to calculate the distance required to move. Reflecting the path of nurse movement, a model was presented for a comprehensive analysis of nursing distance and nursing visibility, which could lead to improvement in the observation and visibility of nurses and the layout of patient rooms or day rooms.

• Atmosphere
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• v.22 no.1
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• pp.13-28
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• 2012

The $PM_{10}$ concentration data is useful for indentifying intensity and a transport way of Asian dust. However, it is difficult to identify them properly due to the limited spatial resolution and coverage. Therefore, a methodology to estimate $PM_{10}$ concentration using visibility data obtained from synoptic observation was developed. To derive the converting function, correlation between visibility and $PM_{10}$ concentration is investigated using visibility and $PM_{10}$ concentration data observed at 20 stations in Korea from 2005 to 2009. To minimize bias due to atmospheric moisture, data with higher relative humidity over a critical value were eliminated while deriving $PM_{10}$-visibility relationship. As a result, an exponentially decreasing function of visibility is obtained under the condition that relative humidity is less than 82%. Verification of the visibility converting function to $PM_{10}$ concentration was carried out for the dust cases in 2010. It was found that spatial distributions of $PM_{10}$ calculated by visibility are in good agreement with the observed $PM_{10}$ distribution, especially for the strong dust cases in 2010. And correlation between the derived and observed $PM_{10}$ concentration was 0.63. We applied the function to obtain distributions of $PM_{10}$ concentration over North Korea, in which concentration data are not available, and compared them with satellite derived dust index, IODI distributions for dust cases in 2010. It is shown that the visibility function estimates quite similar patterns of dust concentration with IODI image, which suggests that it can contribute for prediction by indentifying transport route of Asian dust.

• Journal of the Optical Society of Korea
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• v.14 no.2
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• pp.121-126
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• 2010

We analyze image visibility of a projection-type integral imaging system without diffuser, in terms of the fill factor, which is determined by the relationship between the exit pupil of the projection system and the size and the focal length of the elemental lens. High fill factor is a requirement for good visibility. Moreover, for psychological reasons, for the same fill factor, better visibility is accomplished using a relatively small elemental lens. In this paper, we study image visibility through basic experiments and results.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.2
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• pp.108-115
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• 2011

This paper describes a new sensor system for mobile robot motion estimation using stereo infrared light sources and a camera. Visibility is being applied to robotic obstacle avoidance path planning and localization. Using simple visibility computation, the environment is partitioned into many visibility sectors. Based on the recognized edges, the sector a robot belongs to is identified and this greatly reduces the search area for localization. Geometric modeling of the vision system enables the estimation of the characteristic pixel position with respect to the robot movement. Finite difference analysis is used for incremental movement and the error sources are investigated. With two characteristic points in the image such as vertices, the robot position and orientation are successfully estimated.

• Journal of Urban Science
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• v.9 no.1
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• pp.61-68
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• 2020

Steps are very common features in our living environment. Unfortunately, the occurrence of accidents on steps is thus inevitable. A failed visibility to recognize a step remains the most common attribute in these accidents. In this research, sensory scales of step visibility were created in order to examine the effects of two factors on step visibility in sensory testing methods; observation height from floor and eye condition while viewing a step from the descending direction. Results of sensory tests revealed strong influence of eye condition on step visibility. Influence of visual characteristics of each step was also examined and clarified.

• Journal of Korea Society of Industrial Information Systems
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• v.6 no.1
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• pp.77-81
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• 2001

Good visibility is essential for drivers. Especially it may be critical when drivers are passing through a tunnel. Lighting is one of the major factors that contribute to or detract from visibility in a tunnel. In order to enhance the visibility a new lighting technique has been proposed: counter-beam. This paper proposes a new scheme for tunnel lighting design and analyzes the counter-beam lighting technique by showing the contrast effect of it. Different situations are set and simulated. This study is expected to contribute improving the visibility in tunnels.

• Journal of Korean Society for Atmospheric Environment
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• v.12 no.4
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• pp.377-387
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• 1996

This study was carried out to monitor the visibility including measurement and analysis of the various parameters such as particle size distribution, chemical composition, and meteorotical conditions to understand the characteristics and causes of this phenomenon. According to the analysis of intensive sampling, $SO_4^{2-}, NO-3^-, Cl^-, NH_4^+$ ion concentration increased together with the mass concentration around 1 $\mu$m in the case of low visibility. $(NH_4)_2SO_4, NH_4NO_3$, and $NH_4Cl$ were thought to be the major components of fine particles. The statistical analysis showed that the scattering effect of particle was 81.2%, the absorption effect was 14.9%. Therefore, these effects were the major factors to reduce the visibility. In conclusion, the visibility was reduced by the fine particle of sulfate (18.6%), nitrate (14.2%), organic carbon (10.8%), element carbon (25.8%), and residual (24.8%) during this study.